As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Traditionally, DC/DC voltage regulation down devices (VRDs) have had fixed designs with operating efficiency that is maximized for higher current loads to ensure proper thermal management. Such approaches tend to compromise operating efficiency when operating in lighter current load ranges. Various techniques have been proposed to improve VRD efficiencies in the lighter load ranges, including phase-shedding, gate voltage adjustment, diode emulation, frequency reduction, baby buck, etc. Use of diode emulation at light load conditions has demonstrated minor improvement to VRD operating efficiency, but this minor efficiency improvement is accompanied by complications and required compromises such as an increased bill of materials (BOM) cost and a negative impact on performance. Moreover, use of diode emulation makes accurate detection of zero-crossing current difficult when employing common techniques such as use of inductor direct current resistance (DCR) circuitry or monitoring the phase node to detect zero crossing. As the actual signal is embedded within the noise, these traditional methods are not accurate. Additionally, during diode emulation mode, the power stage transfer function is different than when operating a VRD in continuous conduction mode (CCM) such that the control loop bandwidth in diode emulation mode is reduced as compared to the CCM mode. This in turn may require additional circuits to make sure the VRD seamlessly transitions between these two operating behaviors, especially during transients.
It has also been common to reduce the switching frequency at light current loads in an effort to increase the VR efficiency by lowering the switching losses in the switching FETs. In this regard, switching frequency may be greatly reduced as the load drops, e.g., from about 300 Khz to about 2 kz as an example. Most VRD controllers and power switches have a minimum on-time requirement, however, reducing the switching frequency acts to increase the off time of these components. This results in the need for an increased number of output capacitors to keep the output ripple within specification. Another drawback of reducing the switching frequency during low current loads is a negative impact on the transient response. This also results in a need for additional capacitors, and additional circuits may be required for operation during occurrence of transients.